1. Field of the Invention
The present invention relates to building and landscaping materials and, more specifically, to blocks for building walls and to shaped hollow blocks for lining bank slopes.
2. Disclosure Statement Under 37 CFR 1.56(a)
This disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness, and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also, the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments subsequent in time or priority.
Shaped blocks for building dry walls or walls without mortar, for building retaining walls or revetment walls and for stabilizing slopes as protection against erosion damage or slides are known. Such shaped blocks are frequently laid in courses in an open form of construction, so that the intervening spaces, resembling the berms in terraced lining, can be grassed over. In this direction, a new approach was marked by a bank block according to German Patent Publication No. 25 37 408.
This shaped block is a box-shaped precast concrete block, open towards the rear and having a front wall, two side walls and a base. The two side walls are extended, by a small amount, to below the base, so that channels are formed in the base, on both sides, such that shaped blocks laid in courses engage into each other by means of an indentation produced thereby. In this way, a type of gravity wall is produced, having the dead weight of the blocks and the weight of the earth material, filled into the void space, as weight per unit area.
In the case of the shaped blocks described, disadvantages result from the indentation, due, on the one hand, to a high weight of the blocks, of about 50 kilograms (kg): this high weight resulting from the dimensions between the channels, such dimensions being necessary for convex or concave wall curvatures, and, on the other hand, to the requirement for a large number of shaped blocks per unit area of wall. Thus, for example, eight blocks are required per square meter (m.sup.2) of wall and a steepest wall slope of 3:1 and a smallest radius of curvature of approximately 2 meters (m) can, respectively, be achieved.
It has become evident that, for many cases, particularly in the case of terracing the ground surrounding detached houses, where slopes of 1 m to 2 m at the most are to be reinforced, these known shaped blocks were too expensive and, moreover, insufficiently versatile for many applications.
Also, slope blocks of that type cannot be used well for lining bank slopes in the region of the ground water level, because they cannot anywhere form a closure against the undisturbed earth or against dumped earth or fill.
Experiments and tests were also carried out with a thickened base, to increase the weight, without depressions in the base for forming sealing interlocks between side walls and base, and additionally, with a transverse wall parallel to the face wall and with external wing-like side interlocks on the side walls. Compared to conventional lining using naturally broken stone, slope blocks of this type are, of course, significantly more expensive; they can, however, be grassed over from the water line in a simple manner, whilst below the water line the depressions can be filled with large pebbles in order thereby to increase the weight of the slope blocks. Experience, however, has shown that all these above measures together do not suffice to give the natural appearance to a watercourse having curved and straight places, because adequate closure against the earth is not ensured when the blocks are laid in courses on each other at an angle, and there is accordingly a danger of washout.